A product of which the manufacturing process is completed in a clean room, for example a pellicle (hereinafter when the explanation only refers to a pellicle, it should be taken as an example representing other such products), often ends up with being contained in a container specially designed for the particular product, such as a pellicle case; however, if the container is brought out of the clean room as it is, the container is liable to attract the dust in the air so that when the container is brought into a clean room and opened for the removal of the pellicle, the pellicle may collect some of the dust from the container and some other part of the dust may soil the clean room as well.
Hence, a pellicle encased is usually shipped, on account of this fact, after being wrapped in two or more bags made of an air-tight film material, the innermost bag containing the encased pellicle and being inside the next innermost bag and so on, so as to avoid dust, and when, for example, a pellicle is to be brought in a clean room for use, the outermost bag is removed immediately before the bagged pellicle is brought into the clean room.
In order to keep clean a pellicle manufactured in a clean room as well as its container, it is necessary to pack them with a careful attention, and to this end, heretofore, a packing bag has been hermetically closed by being sealed with heat, or has been provided with a zipper (such as a rail fastener) for secure closing, or has had its mouth completely sealed with an adhesive tape. Furthermore, two or more of these procedures have been combined to achieve a perfectly sealed packaging for shipment.
However, while the product is safe from being contaminated thanks to the faultless packaging, the multi-bag packaging, especially when the number of the bags exceeds three or four, renders the opening operation troublesome and in a case where a bag is thermally sealed, a person opening the package must use a pair of scissors or a knife so that extra tools are in need and what is more the cut face would become a new source of contaminant particles. Also, in the case of a bag with a zipper, the cost is increased and the zipper would allow some foreign particles to pass through it.